JEFFERSON COUNTY, Colo. (CBS4) - Her threats sparked a massive manhunt and prompted dozens of Denver-area schools to cancel classes on Wednesday. Investigators warned Sol Pais was armed with a pump-action shotgun and considered extremely dangerous. After Pais was found dead, we learned more about how she obtained the weapon.

Jefferson County Sheriff Jeff Shrader confirmed the 18-year-old high school student legally purchased the gun at a store in an unincorporated part of the county, after flying from Florida to Colorado.

On Wednesday afternoon, the owner of Colorado Gun Broker said Pais bought the gun from his store.

"She did go through the full background check (4473), and was given a clearance by both NCIC and CBI," Josh Rayburn wrote. "We had no reason to suspect she was a threat to either herself or anyone else."

In Colorado, there is no residency requirement for the purchase of a long gun like the one authorities say Pais bought. You can buy one at the age of 18. That is different from a handgun. You have to be 21 to purchase a handgun – and for a handgun purchase you have to show a Colorado ID.

There is also no waiting period for weapons purchases in Colorado and the background check usually takes a matter of minutes.

RELATED: Who Was Sol Pais?

Investigators say Pais died from a self-inflicted gunshot wound. She was found Wednesday morning half a mile away from Echo Lake Lodge up Mount Evans Road, near where the road is currently closed for the season.